docstr: Data is search space
          
docstr_tok: ["Data","is","search","space"]
code: def handle_initialize(self, data):
      """Data is search space"""
      _logger.info("Initial search space: %s", data)
      self.tuner.update_search_space(data)
      self.send(CommandType.Initialized, "")
  
imports: import logging
  from collections import defaultdict
  from nni import NoMoreTrialError
  from nni.assessor import AssessResult
  from .common import multi_phase_enabled
  from .env_vars import dispatcher_env_vars
  from .msg_dispatcher_base import MsgDispatcherBase
  from .tuner_command_channel import CommandType
  from ..common.serializer import dump, load
  from ..utils import MetricType
label_desc: Use image node_id 4 for calling the MsgDispatcher obj's underlying member method code with example usage: obj.handle_initialize(data) without return types